Different string comparison

duckdb · May 8, 2021 · 93b2d99 · 93b2d99
1 parent c58ea95
commit 93b2d99
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Showing 2 changed files with 11 additions and 6 deletions.
diff --git a/src/include/duckdb/common/operator/comparison_operators.hpp b/src/include/duckdb/common/operator/comparison_operators.hpp
@@ -89,15 +89,20 @@ inline bool LessThan::Operation(bool left, bool right) {
 struct StringComparisonOperators {
 	template <bool INVERSE>
 	static inline bool EqualsOrNot(const string_t a, const string_t b) {
-		if (a.IsInlined()) {
+		auto alen = a.value.inlined.length;
+		auto blen = b.value.inlined.length;
+		if (alen != blen) {
+			return false;
+		}
+		if (alen <= string_t::INLINE_LENGTH) {
 			// small string: compare entire string
-			if (memcmp(&a, &b, sizeof(string_t)) == 0) {
+			if (memcmp(&a.value.inlined.inlined, &b.value.inlined.inlined, alen) == 0) {
 				// entire string is equal
 				return INVERSE ? false : true;
 			}
 		} else {
-			// large string: first check prefix and length
-			if (memcmp(&a, &b, sizeof(uint32_t) + string_t::PREFIX_LENGTH) == 0) {
+			// large string: first check prefix
+			if (memcmp(a.value.pointer.prefix, b.value.pointer.prefix, string_t::PREFIX_LENGTH) == 0) {
 				// prefix and length are equal: check main string
 				if (memcmp(a.value.pointer.ptr, b.value.pointer.ptr, a.GetSize()) == 0) {
 					// entire string is equal

diff --git a/src/include/duckdb/common/types/string_type.hpp b/src/include/duckdb/common/types/string_type.hpp
@@ -33,7 +33,7 @@ struct string_t {
 		if (IsInlined()) {
 			// zero initialize the prefix first
 			// this makes sure that strings with length smaller than 4 still have an equal prefix
-			memset(value.inlined.inlined, 0, INLINE_LENGTH);
+			memset(value.inlined.inlined, 0, PREFIX_LENGTH);
 			if (GetSize() == 0) {
 				return;
 			}
@@ -89,7 +89,7 @@ struct string_t {
 		auto dataptr = (char *)GetDataUnsafe();
 		if (GetSize() <= INLINE_LENGTH) {
 			// fill prefix with zeros if the length is smaller than the prefix length
-			for (idx_t i = GetSize(); i < INLINE_LENGTH; i++) {
+			for (idx_t i = GetSize(); i < PREFIX_LENGTH; i++) {
 				value.inlined.inlined[i] = '\0';
 			}
 		} else {